Dapsone is useful for conditions like dermatitis herpetiformis, acne (topical), and certain infections. But it’s one of those drugs where a little preparation makes a big difference. Read this if you or someone you care for is starting dapsone—or if you want to spot trouble early.
The two issues to know first are hemolysis (red blood cell breakdown) and methemoglobinemia (reduced oxygen delivery). Hemolysis causes tiredness, dark urine, rapid heartbeat, or low blood counts. Methemoglobinemia makes you look bluish, feel short of breath, or very tired; oxygen levels can drop even though the lungs are fine. Both are more likely if you have G6PD deficiency or if you take other oxidant medicines.
Another serious problem is a drug hypersensitivity syndrome (sometimes called DRESS). It usually starts in the first few weeks with fever, widespread rash, swollen glands, or liver problems. If that happens, stop dapsone and get medical help quickly.
Before you start: get a G6PD test. It’s the single most useful check because G6PD-deficient people are at high risk of hemolysis. Also do baseline bloods—CBC (full blood count) and liver tests—so your doctor has something to compare later.
After starting dapsone, expect follow-up blood tests. A common practical plan is: recheck CBC and liver tests at 2–4 weeks, again at one and three months, then every 3 months if things are stable. If you feel unwell between checks (fever, new rash, sore throat, jaundice, dark pee, severe breathlessness), call your clinician and stop the drug until they advise.
Topical dapsone has far fewer systemic risks, but if you use it on large body areas or with damaged skin, some absorption can occur. The monitoring approach is similar if your prescriber is concerned.
Drug interactions: avoid combining dapsone with other strong oxidants (certain antibiotics and antimalarials) without advice. Some medicines can change dapsone levels—so tell your doctor about everything you take, including supplements.
Pregnancy and breastfeeding: dapsone crosses the placenta and shows up in breastmilk. Doctors balance risks and benefits case by case; newborns may be more vulnerable to hemolysis, so extra caution is needed.
Practical tips: carry a list of your medications, write down allergy history, and mention G6PD status on medical forms. If you notice blue lips, severe fatigue, dark urine, fever with rash, or yellow skin/eyes, seek urgent care.
Dapsone works well for many people when used carefully. With a baseline G6PD test, routine blood checks, and quick action on warning signs, you can reduce risk and get the benefit the drug offers.
